Silsesquioxane dispersions have been found to be useful for treatment of carpets and textiles in concert with fluorochemical resins to impart oil and water repellency and general resistance to soil as disclosed in U.S. Pat. No. 6,225,403 (Knowlton). However, where such dispersions are produced by condensation reactions using alkyltrialkoxysilanes, unacceptably large amounts of alkoxy compounds (for example methanol in the case of alkyltrimethoxysilanes) may be present as a byproduct of the silane reaction. Alkoxy compounds such as methanol are generally undesirable in treatment compositions and on treated articles but cannot be removed effectively during the condensation reaction process since the silanes are sufficiently volatile that a removal process is likely to remove the desired reactant as well. Upon completion of the reaction, the usual methods of cleaning and re-dispersing the silsesquioxane particles are cumbersome and are likely to result in extensive and undesirable agglomeration of the reaction products and consequent loss of both effectiveness and yield.
Surface-modified silica dispersions that have been produced by condensation reactions with alternative reagents result in alternative byproducts which are also undesirable, examples being triethoxysilanes yielding ethanol, and halogenated silanes yielding halogen acids. Halogen acids can cause undesirable agglomeration owing to related changes in pH, while ethanol is undesirable for articles such as carpet because, like methanol, it is a volatile organic compound.
Several methods are potentially useful to remove the above mentioned alcohol reaction byproducts from water. However, it has been found that many are unsuitable when applied to silsesquioxane dispersions of the kind applicable to carpets and textiles. In particular, it has been found that undesirable agglomeration of silsesquioxane dispersions results when evaporation is employed to remove either methanol or ethanol from such systems. Dispersions that are particularly applicable to carpets and textiles have typically been formed in aqueous systems buffered with ammonium counter-ions to stabilize them. The ammonium-ammonia equilibrium may be adversely affected by evaporation, so that the resulting system may no longer support the dispersion of all of the particles, and precipitation of some or all of the suspended particles of the dispersion may ensue. It has also been observed that silsesquioxane dispersions built from silica cores suffer from the same issues that are encountered with the surface-modified silica dispersions.
US patent application number 2008/0216709A1 (Steingrover) teaches that acidic aminoalkylsilane modified silica particles are stable in acidic aqueous solutions in contrast to other alkylsilane materials. However, the organic amine functionality disclosed by Steingrover is not capable of creating hydrophobic, soil resistant and oil repellent fabrics.